1. Field of the Invention
The present invention relates to mine roof props and, more particularly, to a yieldable mine roof prop having two telescoping conduits, a clamp assembly, and a yield section having a collapsible insert.
2. Brief Description of the Prior Art
A mine roof support system having two yielding props connected to one another by a support cross member is known. The yieldable props in the known mine roof support system each include a clamp assembly which includes a clamp having a first split conduit, a second split conduit, at least one U-shaped bolt, an arch-shaped brace, and internally threaded nuts.
In one arrangement of a yieldable prop, an inner conduit is slidably mounted into an outer conduit and held in position by a clamp assembly. As a compression load, e.g., a shifting mine tunnel roof, acts on the prop, the first tube slides into the second tube. Although this is acceptable, there are limitations, e.g., the force of the clamp assembly controls the load that the prop can take before it compresses. Because the props are usually manually set and the clamp assembly manually adjusted in the mines, there is a variation in the compressive load each prop can support before collapsing.
It would be advantageous to provide a yieldable prop that does not have the limitations of the available yieldable props.